The Guardian considers the hype of Charlotte Roche’s Feuchtgebiete.

For whether it is the fantasies about sex, the polemics against the use of deodorants, the avocado cores grown specially for use in masturbation, or the detailed and inventive passages of scatological or genital description, Wetlands has left few indifferent.

This seems to be the only hit for the curious term avocado core on a UK site. It sounds a bit like an apple core. It seems to mean Avocadokern/avocado pit or avocado stone.